I agree that it would be great to have BirdieSync running on Linux. But it's mainly a question of time. The problem is the same for Mac OS. It's already necessary to spend time on many environments which constantly evolve (Android, iPhone, Windows, Thunderbird). Some work has already be done to prepare a possible port but some work would remain to be done (some specific adaptations, installer, all the external libraries ready for Linux, testing, etc.). But it's also necessary to make BirdieSync evolve too. So at the moment, time is simply missing to support a new operating system. So maybe one day but I still cannot tell you when.